#!/usr/bin/env python
# encoding: utf-8
#
# Copyright 2022 Spotify AB
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import tensorflow as tf


def log_base_b(x: tf.Tensor, base: int) -> tf.Tensor:
    """
    Compute log_b(x)
    Args:
        x : input
        base : log base. E.g. for log10 base=10
    Returns:
        log_base(x)
    """
    numerator = tf.math.log(x)
    denominator = tf.math.log(tf.constant(base, dtype=numerator.dtype))
    return numerator / denominator
